Defining the SEP environment for specifications using the SAPPHIRE model

Present standards for the solar energetic particle radiation environment in space prescribe a somewhat disparate set of methods for the determination of environment specifications. Herein a new model is presented to cover all SEP environment time-scales across all relevant species in a consistent, probabilistic manner; the Solar Accumulated and Peak Proton and Heavy Ion Radiation Environment (SAPPHIRE) model. This model builds on earlier work regarding the probabilistic modelling methodology but is greatly enhanced making use of updates to the ESA's SEPEM (Solar Energetic Particle Environment Modelling) Reference Data Set (RDS) for protons and an extension to include helium. A careful processing of heavier ion data has been carried out to extend the helium model to heavier ions. Model outputs include mission cumulative fluence, worst-case event fluence and peak fluxes for proton spectra, helium spectra and heavy ion spectra also included as a function of Linear Energy Transfer (LET). As a verification of the robustness of the procedure the proton model outputs are compared to a similar model based solely on data from neutron monitors.